Strain gauge

Abstract

A strain gauge includes a substrate, a resistor formed on the substrate, and two lines. The resistor includes multiple elongated portions. Each of the lines includes a first metal layer and a second metal layer that is laminated on the first metal layer and is formed of a material having lower volume resistivity than the first metal layer. In plan view, an outer edge of the first metal layer is exposed from the second metal layer. In plan view, an end of the second metal layer on a first end side in a first direction protrudes further toward the first end side in the first direction than an end of a space that is situated between the first metal layer and an elongated portion adjacent to the first metal layer.

The invention claimed is: 
     
       1. A strain gauge comprising: a substrate; a resistor formed on the substrate; and two lines formed on the substrate and coupled in series to both ends of the resistor, wherein the resistor includes multiple elongated portions, whose longitudinal directions are aligned with a first direction and which are coupled in series with each other, are arranged side by side, wherein a first line of the lines is disposed parallel to a first elongated portion, among the multiple elongated portions, that is located at a first end in a second direction perpendicular to the first direction, wherein the first line is coupled to a first end of the first elongated portion in the first direction, wherein a second line of the lines is disposed parallel to a second elongated portion, among the multiple elongated portions, that is located at a second end in the second direction, wherein the second line is coupled to a first end of the second elongated portion in the first direction, wherein each of the lines includes a first metal layer and a second metal layer that is laminated on the first metal layer and is formed of a material having lower volume resistivity than the first metal layer, wherein in plan view, an outer edge of the first metal layer is exposed from the second metal layer, wherein in plan view, an end of the second metal layer on a first end side in the first direction protrudes further toward the first end side in the first direction than an end of a space that is situated between the first metal layer and a corresponding elongated portion, among the first elongated portion and the second elongated portion, adjacent to the first metal layer. 
     
     
       2. The strain gauge according to  claim 1 , wherein a length by which the end of the second metal layer on the first end side in the first direction protrudes toward the first end side in the first direction, with respect to the end of the space on the first end side in the first direction, is 1 μm or more. 
     
     
       3. The strain gauge according to  claim 2 , wherein the length by which the end of the second metal layer protrudes is equal to or greater than a length of each elongated portion of the multiple elongated portions in the second direction. 
     
     
       4. The strain gauge according to  claim 3 , wherein the length of the elongated portion in the second direction is 5 μm or more. 
     
     
       5. The strain gauge according to  claim 1 , wherein a length in the first direction between an end of the first metal layer on the first end side in the first direction and the end of the second metal layer on the first end side in the first direction is 5 m or more. 
     
     
       6. The strain gauge according to  claim 1 , wherein the second metal layer is formed of a material having superior elasticity to the first metal layer. 
     
     
       7. The strain gauge according to  claim 1 , wherein the first metal layer is integrally formed with the resistor by a same material. 
     
     
       8. The strain gauge according to  claim 1 , wherein the resistor is formed of a film including Cr, CrN, and Cr 2 N.